Au-decorated ZnO nanowires for the detection of NO2 gas: A DFT study

Abstract

The adsorption of NO2 on a pristine and Au-decorated ZnO nanowire (NW) was investigated using density functional theory (DFT) calculations to determine the role of Au-decoration on the gas sensing response of ZnO NW. Au decoration changed the electronic structure of ZnO NW, which could improve the NO2adsorption gas molecules on the surface of Au-decorated ZnO NW. Bader charge analysis showed that the enhanced response of Au-decorated ZnO NW gas sensor to NO2 gas was related mainly to the gas adsorption on Au atoms. The NO2 molecule adsorbed on the Au atom captures 0.54 e from the Au-decorated ZnO NW, which is higher than that of the pristine one. Calculations of the charge density difference and geometry revealed the catalytic role of Au for NO2 adsorption.